For medical procedures, minimally invasive procedures are preferred over conventional techniques wherein the patient's body cavity is open to permit the surgeon's hands access to internal organs. Thus, there is a need for a highly controllable yet minimally sized system to facilitate imaging, diagnosis, and treatment of tissues which may lie deep within a patient, and which may be accessed via naturally-occurring pathways, such as blood vessels, other lumens, via surgically-created wounds of minimized size, or combinations thereof.
Currently known minimally invasive procedures for the treatment of cardiac, vascular, and other disease conditions use manually or robotically actuated instruments, which may be inserted transcutaneously into body spaces such as the thorax or peritoneum, transcutaneously or percutaneously into lumens such as the blood vessels, through natural orifices and/or lumens such as the mouth and/or upper gastrointestinal tract, etc. Manually and robotically-navigated interventional systems and devices, such as steerable catheters, are well suited for performing a variety of minimally invasive procedures. Manually-navigated catheters generally have one or more handles extending from their proximal end with which the operator may steer the pertinent instrument. Robotically-navigated catheters may have a proximal interface configured to interface with a catheter driver comprising, for example, one or more motors configured to induce navigation of the catheter in response to computer-based automation commands input by the operator at a master input device in the form of a work station.
In the field of electrophysiology, robotic catheter navigation systems, such as the Sensei® Robotic Catheter System (manufactured by Hansen Medical, Inc.), have helped clinicians gain more catheter control that accurately translates the clinician's hand motions at the workstation to the catheter inside the patient's heart, reduce overall procedures (which can last up to four hours), and reduce radiation exposure due to fluoroscopic imaging necessary to observe the catheter relative to the patient anatomy, and in the case of electrophysiology, within the relevant chamber in the heart. The Sensei® Robotic Catheter System employs a steerable outer catheter and a steerable inner electrophysiology (EP) catheter, which can be manually introduced into the patient's heart in a conventional manner. The outer and inner catheters are arranged in an “over the wire” telescoping arrangement that work together to advance through the tortuous anatomy of the patient. The outer catheter, often referred to as a guiding sheath, provides a steerable pathway for the inner catheter. Proximal adapters on the outer guide sheath and inner EP catheter can then be connected to the catheter driver, after which the distal ends of the outer sheath and inner EP catheter can be robotically manipulated in the heart chamber within six degrees of freedom (axial, roll, and pitch for each) via operation of the Sensei® Robotic Catheter System.
While the Sensei® Robotic Catheter System is quite useful in performing robotic manipulations at the operational site of the patient, it is desirable to employ robotic catheter systems capable of allowing a physician to access various target sites within the human vascular system. In contrast to the Sensei® Robotic Catheter System, which may be used in conjunction with sheaths and catheters that are both axially and laterally rigid, robotic catheter systems designed to facilitate access to the desired target sites in the human vascular system require simultaneous articulation of the distal tip with continued insertion or retraction of an outer guide sheath and an inner catheter. As such, the outer guide sheath and inner catheter should be laterally flexible, but axially rigid to resist the high axial loads being applied to articulate the outer guide sheath or inner catheter, in order to track through the tortuous anatomy of the patient. In this scenario, the inner catheter, sometimes called the leader catheter extends beyond the outer sheath and is used to control and bend a guidewire that runs all the way through the leader catheter in an over-the-wire configuration. The inner catheter also works in conjunction with the outer guide sheath and guidewire in a telescoping motion to inchworm the catheter system through the tortuous anatomy. Once the guidewire has been positioned beyond the target anatomical location, the leader catheter is usually removed so that a therapeutic device can be passed through the steerable sheath and manually operated.
As shown in FIG. 1, robotic catheter systems typically employ a robotic instrument driver 1 to provide robotic insertion and refraction actuation, as well as robotic steering actuation, to a telescoping assembly of elongate flexible instruments. The instrument driver 1 comprises a housing 2 that contains motors (not shown) for providing the robotic actuators to the telescoping assembly, which may include an outer steerable guide sheath 3, an inner steerable leader catheter 4 disposed within the sheath catheter, and a conventional guidewire 5 disposed within the leader catheter 4.
The robotic instrument driver 1 may robotically insert/retract the leader catheter 4 relative to the sheath catheter 3. To this end, the proximal ends of the guide sheath 3 and leader catheter 4 are mechanically interfaced to the instrument driver 1 in such a manner that they may be axially translated relative to each other via operation of the motors, thereby effecting insertion or retraction movements of the respective guide sheath 3 and leader catheter 4. In the illustrated embodiment, the guide sheath 3 and leader catheter 4 respectively include proximal steering adapters 6, 7 (“splayers”) mounted to associated mounting plates 8, 9 on a top portion of the instrument driver 1. In the illustrated embodiment, each of the proximal adapters 6, 7 can be actuated via motors (not shown) within the housing 2 of the instrument driver 1 to deflect or articulate the distal ends of the respective guide sheath 3 and leader catheter 4 in any direction.
Unlike the steerable guide sheath 3 and leader catheter 4, the distal ends of which can be robotically articulated via the instrument driver 1, the guidewire 5 is conventional, and thus, its distal end is not capable of being robotically articulated. Instead, as with most conventional guidewires, the guidewire 5 may be manipulated by inserting, retracting, or rolling or by simultaneously rolling while axially displacing the guidewire. In a non-robotic environment, such manipulations can be accomplished by pinching the proximal end of the guidewire between the forefinger and thumb of the physician and moving the forefinger relative to the thumb while axially displacing the guidewire.
In order to navigate the guide sheath 3 and leader catheter 4 through the tortuous anatomy of a patient, it is desirable that these components be laterally flexible. However, the flexibility of the leader catheter 4 may create issues when performing the robotic insertion actuation. In particular, due to the flexibility of the leader catheter 4 and the relatively long distance between the mounting plate 9 and the point at which the leader catheter 4 is contained within the guide sheath 3, the leader catheter 4 may buckle, thereby preventing it, or at least hindering it, from axially translating within the guide sheath 3. Although “passive” anti-buckling devices may be used to add lateral support to the leader catheter 4, thereby preventing the leader catheter 4 from buckling, these anti-buckling devices have length limitations and may be too cumbersome and time-consuming for medical personnel to install.
Furthermore, emulating a manual guidewire manipulation in a robotic catheter system is not a straightforward procedure. For example, although the instrument driver 1 illustrated in FIG. 1 can be designed to robotically insert/retract the guidewire 5 relative to the leader catheter 4 in the same manner in which the instrument 1 robotically inserts/retracts the leader catheter 4 relative to the guide sheath 3, such an arrangement may be impractical. In particular, the incorporation of an additional carriage within the housing 2 will disadvantageously increase the length of the instrument driver 1, which must accommodate the telescoping assembly when assuming a maximum retraction between the leader catheter 4 and guide sheath 3 and between the guidewire 5 and leader catheter 4. The increased size of the instrument driver 1 may be impractical and too big and heavy to be mounted on a table in a catheter lab environment. Thus, it is preferable that any drive device that inserts/retracts the guidewire 5 relative to the leader catheter 4 be immobile relative to the proximal end of the leader catheter 4, e.g., by locating it on the same mounting plate 9 that is associated with the leader catheter 4. This drive device must also be capable of rolling the guidewire 5.
Furthermore, the use of an additional carriage for the guidewire 5 would also require the installation of an additional “passive” anti-buckling device. Because medical personnel often exchange out guidewires that are as long as 300 cm in length, the use of a “passive” anti-buckling device not only may be tedious for medical personnel to install, the extended length of the anti-buckling device due to the length of the guidewire may render the anti-buckling device functionally impractical.
Additional complexities in emulating a manual guidewire manipulation in a robotic catheter system are slipping/buckling of the guidewire during manipulation and controlling or varying guidewire insertion/retraction speeds depending on the procedure or task. Guidewires may also exist in varying conditions, for example a guidewire may be wet with saline, or contaminated with blood or other bodily fluids. Many guidewires have hydrophilic coatings whose properties change with how dry or wet it is. In manual procedures, the doctor may adjust the grip on the wire to shorten it for higher force insertions to reduce risk of buckling. Alternatively, the doctor can lengthen the insertion strokes in times of low insertion force where increased speed is desirable. The doctor may also use a wet cloth or dry cloth to wet or dry the wire, respectively, to alter the coefficient of friction on the wire to help with insertion or retraction
There, thus, remains a need to provide an improved instrument driver for a robotic catheter system that prevents a guidewire from buckling and improves the control of guidewire manipulation.